1. Field of the Invention
The present invention relates to an aminobenzoic acid derivative, particularly an aminobenzoic acid derivative useful as drugs, and a process for preparing the same.
2. Description of the Related Art
The proportion of patients with unidentified complaints such as abdominal full-consciousness, heartburn, nausea and vomiting among those with gastrointestinal diseases has recently increased steadily and now reaches 60% or above.
Most of these unidentified complaints are caused by functional abnormality of digestive tract. For example, it is known that a patient with epigastric unidentified complaints such as chronic gastrltis is in a state of delayed gastric emptying, while a patient with hypogastric unidentified complaints such as irritable bowel syndrome including abnormal evacuation and abdominal pain as main symptoms is in a state of intestinal hyperanakinezia.
It is ascertained that stress and anxiety are causative of any unidentified complaint, and in this sense, it is not too much to say that unidentified complaint is one of modern diseases.
Dopamine antagonists, musculotropic agents for regulating the movement of smooth muscles and acetylcholine release accelerators are now used in order to ameliorate the above gastrointestinal unidentified complaints. However, dopamine antagonists cause potent adverse reactions such as parkinsonism, so that they must be used carefully; musculotropic agents for regulating the movement of smooth muscles cause adverse reactions such as constipation unfavorably; and acetylcholine release accelerators do not effectively act as an antiemetic or ataractic, thus being unsatisfactory.
Under these circumstances, the present inventors have set about making studies for the purpose of developing a drug which is efficacious in treating all types of patients with gastrointestinal unindentified complaints or gastrointestinal indefinite complaints without causing any potent adverse reaction and exhibits a depressant activity against anxiety which is nearly always found as one of the background factors of such patients.
As a result of the studies, it has been concluded that the above requirements can be fulfilled by a drug exhibiting both a serotonin (hereinafter abbreviated to "5HT.sub.3 ") antagonism and an acetylcholine (hereinafter abbreviated to "ACh") release accelerating activity. Therefore, further studies have been made in order to find a compound exhibiting both the activities at a well-balanced activity ratio to find out that the object can be attained by using an aminobenzoic acid derivative represented by the following general formula (I) or a pharmacologically acceptable salt thereof. The present invention has been accomplished on the basis of this finding.
Although aminobenzoic acid derivatives useful as drugs have been described in Great Britain Patent Publication-A Nos. 1593148/1981 (BEECHAM GROUP LTD., Published on Jul. 15, 1981), 2125398/1984 (DONATSCH P; SANDOZ AG; SANDOZ-PATENT-GMBH; and SANDOZ SA, Published on Mar. 7, 1984) and 2205095/1988 (BRISTOL-MYERS SQIBB CO. and BRISTOL-MYERS CO., Published on Nov. 30, 1988), U.S. Pat. No. 4,797,406/1985 (SANDOZ-PATENT-GMBH; and SANDOZ SA, Published on Apr. 24, 1985) and U.S. Pat. No. 5,001,133/1991 (SANDOZ AG, Published on Mar. 19, 1991), European Patent Publication-A Nos. 189002/1986 (SANDOZ AG, Published on Jul. 30, 1986), 220011/1987 (BEECHAM GROUP PLC., Published on Apr. 29, 1987) and 302699/1989 (FORDONAL SA and WALTON SA, published on Feb. 8, 1989) and Great Britain Patent Publication-B No. 2169292/1988 (SANDOZ LTD., Published on Sep. 21, 1988), the compounds of the present invention are different from them in the chemical structures.